Is wiping with a dry محرمة after urinating sufficient, or is washing necessary to avoid the obsessive thought of drops falling onto one's underwear?

Our pure religion is built upon ease, and among the manifestations of ease is the concession of using istijmar (cleaning with stones or similar dry materials) to remove what exits from the two private parts. Istinja' (cleaning with water) is not obligatory, though it is preferable and better. It is permissible to forgo it in favor of istijmar with stones or what serves a similar purpose, such as tissues and pieces of cloth. The condition for istijmar is that the place of impurity be wiped with stones or what serves a similar purpose three times, and it is recommended to make the number odd. As long as you are merely in doubt about the emission of urine, do not pay attention to it as long as it is a doubt.